"Success looks like an ISIL that no longer threatens our friends, can't accumulate followers and threaten Muslims in Syria, Iraq, or otherwise," McDonough told NBC "Meet the Press" host Chuck Todd. "And that's exactly what success looks like."
To achieve that, the United States will wage a counter-terrorism fight like those in Yemen and Somalia, "where we will take the fight to our enemies without putting our ground troops into the effort," McDonough said, echoing President Barack Obama's prime-time speech last week.
He admitted, like many military experts, that ground troops are needed, but pointed out to Todd that Obama's plan calls for training opposition troops in Iraq and Syria to handle the ground battles.
"That's why we want to make sure that this coalition brings Sunnis to the fight," said McDonough, who appeared not only on the NBC program, but also on ABC, FOX, and CNN's Sunday news shows to discuss the ongoing ISIS situation.
There has been some disagreement on whether to term the fight against ISIS as a war or as a counterterrorism exercise, as President Barack Obama termed the matter in his prime-time address last Wednesday.
"This isn't [about] talking points, but [it's] very serious business," McDonough told ABC "This Week" host Martha Raddatz. "We believe just as we have been at war with al Qaida since the day we got here, here we are at war with ISIL."